1. Field of the Invention
The present invention relates to a lens barrel provided on a film camera, a digital camera and the like, and an imaging apparatus having the lens barrel.
2. Description of the Related Art
Conventionally, film cameras which use a silver halide film were widely spread. However, recently digital cameras capable of capturing an image into a memory without using film have quickly spread. Some of these digital cameras have a zoom mechanism for moving a plurality of optical lenses in an optical axis direction to change the imaging magnification. Japanese Patent Application Laid-Open No. 2001-324663 discusses an example of a zoom lens barrel configuration.
In the configuration discussed in Japanese Patent Application Laid-Open No. 2001-324663, a plurality of lens holding units which hold a plurality of lenses are moved in the optical axis direction by a cam ring, and movement in a rotational direction of the lens holding units is regulated by a rotation regulation unit. This configuration allows the optical lenses to be moved to a designated position.
Recently, with the rapid progress in increasing magnification, there has been an increase in a number of lens groups and in an extended total lens length, so that cameras tend to be larger. Meanwhile, there is a strong demand for a thinner camera, so that there is a need to make the camera as thin as possible when the lens barrel is stored in the camera. One way to make the camera thinner is to shorten a dimension of each barrel tube in the optical axis direction and connect the tubes in a multistage configuration. However, such configuration is difficult to achieve as it involves many restrictions in arranging the tubes without intersecting a plurality of cams.
Japanese Patent No. 3842087 and Japanese Patent Application Laid-Open No. 2002-258378 discuss methods to solve this problem.
Recently, cameras are downsized and their optical systems have greater magnification, so that an amount of lens extension movement is increasing. As a result, a movement of a barrier has to be interlocked with the extension amount of the barrel, and many rotation angles need to follow interlocking movement of the barrier with the barrel. At the same time, a barrier interlocking unit has to be arranged which avoids a cam groove.